Receiver

ABSTRACT

A receiver capable of reducing the number of pads of a semiconductor device used for connection with a tuning circuit. The receiver includes a semiconductor device  100  containing various circuits and a tuning circuit  130  connected as a separate part to this semiconductor device  100 . The semiconductor device  100  has a pad  112  formed on a semiconductor substrate  110 , a processing circuit  114  connected via a capacitor  120  to the pad  112 , and a D/A converter  122  connected via a resistor  124  to the pad  112 . A tuning voltage generated by the D/A converter  122  is applied via the pad  112  to the tuning circuit  130 . Moreover, an output signal of the tuning circuit  130  is supplied to the pad  112  and fed via the capacitor  120  to the processing circuit  114.

TECHNICAL FIELD

The present invention relates to a receiver equipped with a tuningcircuit and a semiconductor device connected in its subsequent stage.

BACKGROUND ART

If various kinds of entire apparatuses can be formed on onesemiconductor substrate, there are various advantages such as productionsimplification, but in actual circuits, there are circuits suitable fortransformation-into-semiconductor, circuits not suitable fortransformation-into-semiconductor, or circuits which are impossible totransform them into semiconductors. For this reason, plenty of externalcomponents besides one or plural semiconductor devices which areconstituted by using a semiconductor substrate are required. Forexample, in the case of a receiver, a high frequency circuit where atuning circuit using a capacitor and a coil is included is prepared as aseparate component, all or some of subsequent stages of circuits areformed as a semiconductor device on a semiconductor substrate, and thereceiver is constituted by connecting these on a printed circuit board.

Generally, a pad formed on a semiconductor substrate is used so as toconnect a preceding stage of circuit and a subsequent stage ofsemiconductor device in this manner.

FIG. 2 is a diagram showing a conventional connection status of a tuningcircuit and a semiconductor device connected in its subsequent stage. Aparallel resonance circuit consisting of a coil and variable capacitancediodes is included in a tuning circuit 200, and a tuning frequency ischanged by changing a reverse bias of tuning voltage applied to thevariable capacitance diodes. In addition, in a semiconductor device 210connected in the subsequent stage of this tuning circuit 200, a pad 214into which an output signal of the tuning circuit 200 is inputted, and apad 216 for applying a tuning voltage to the variable capacitance diodesin the tuning circuit 200 are formed on a semiconductor substrate 212.

By the way, as mentioned above, in the semiconductor device 210, twopads 214 and 216 used for connection between with one tuning circuit 200are required. In particular, in a general receiver, there was a problemthat, since two or more sets of parallel resonance circuits by a coiland variable capacitance diodes which were provided in the tuningcircuit 200 were provided, the number of the pads for tuning circuitsformed on the semiconductor substrate 212 was required twice of thenumber of these parallel resonance circuits, and hence, an area whichthese pads occupied became large. In particular, although the number ofpads for outputting and inputting signals among plenty of externalcomponents increases when the high densification and functionality ofthe semiconductor device 210 are achieved, in order to miniaturize thesemiconductor device 210, it is desired to reduce the number of padsformed on the semiconductor substrate 212, and in particular, the numberof pads for tuning circuits with a large ratio among them.

DISCLOSURE OF THE INVENTION

The present invention is created in view of such a point, and its objectis to provide a receiver which can reduce the number of pads of asemiconductor device used for connection with a tuning circuit.

The receiver of the present invention has a tuning circuit and asemiconductor device including a processing circuit, into which anoutput signal of this tuning circuit is inputted, and a tuning voltagegenerating circuit which generates a tuning voltage changing a tuningfrequency of the tuning circuit. In addition, the tuning circuit hasvariable capacitance diodes whose electrostatic capacity is madevariable by a tuning voltage being applied. The semiconductor device hasa common pad to which not only an output terminal of the tuning voltagegenerating circuit is connected, but also an input terminal of theprocessing circuit is connected via a capacitor. Then, one terminal ofthe variable capacitance diodes and the pad are connected. Since it ispossible to commonly use a pad for the application of the tuning voltageand a pad for input/output of a signal between the tuning circuit andprocessing circuit by outputting and inputting an output signal of thistuning circuit by using a connection wire of applying the tuning voltageto the variable capacitance diodes which constitute the tuning circuit,it is possible to reduce the number of pads of the semiconductor devicewhich are used for connection with the tuning circuit.

In addition, it is desirable that the processing circuit included in thesemiconductor device, the tuning voltage generating circuit, pad, andcapacitor are formed on a semiconductor substrate. Thereby, since a padfor connection inside the semiconductor device becomes unnecessary, itbecomes possible to reduce the number of pads necessary in the entiresemiconductor device.

Furthermore, it is desirable that the above-mentioned tuning circuit hasa parallel resonance circuit where a coil and the variable capacitancediodes are parallel-connected. Owing to this, it becomes possible tofetch a signal component, tuned by the parallel resonance circuit, fromone terminal of the variable capacitance diodes.

Moreover, it is desirable that the above-mentioned tuning circuit isequipped with two or more sets of parallel resonance circuits. Thereby,the effect of reducing the number of pads of the semiconductor devicebecomes further remarkable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the partial structure of a receiver of anembodiment; and

FIG. 2 is a diagram showing a conventional connection status of a tuningcircuit and a semiconductor device connected in its subsequent stage.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, a receiver according to an embodiment where the presentinvention is applied will be described with referring to drawings.

FIG. 1 is a diagram showing the partial structure of the receiver of theembodiment. As shown in FIG. 1, the receiver of this embodiment has asemiconductor device 100, in which various kinds of circuits areincluded, and a tuning circuit 130 connected to this semiconductordevice 100 as a separate component.

The tuning circuit 130 comprises a coil 132 and two variable capacitancediodes 134 and 136 whose cathode sides are connected each other. The twoanode sides of variable capacitance diodes 134 and 136 are connected toboth ends of the coil 132 respectively, and the parallel resonancecircuit which determines a tuning frequency is constituted. It ispossible to adjust the tuning frequency of this tuning circuit 130 bychanging a reverse bias of tuning voltage applied from the external tothe two cathode sides of the variable capacitance diodes 134 and 136.

The semiconductor device 100 has a pad 112 formed on the semiconductorsubstrate 110, a processing circuit 114 connected to the pad 112 via acapacitor 120, and a digital-to-analog (D/A) converter 122 connected tothe pad 112 via a resistor 124. The processing circuit 114 performspredetermined processing to a signal inputted from the tuning circuit130 via the pad 112. For example, after receiving the output signal ofthe tuning circuit 130 in an FET 116 and performing high frequencyamplification of this signal, the processing circuit 114 performsfrequency conversion processing of mixing a local oscillation signal.The capacitor 120 is provided for impedance matching or removal ofdirect current. The digital-to-analog converter 122 is a tuning voltagegenerating circuit which generates the tuning voltage of the tuningcircuit 130, and the generated tuning voltage is applied to the tuningcircuit 130 via the resistor 124, which has sufficiently largeresistance, and the pad 112.

The receiver of this embodiment has such structure, and its operationwill be explained.

The digital-to-analog converter 122 generates a predetermined tuningvoltage. This tuning voltage is applied to the cathode sides of thevariable capacitance diodes 134 and 136 in the tuning circuit 130 viathe resistor 124 and pad 112. In addition, the output signal of thetuning circuit 130 is transmitted via the connection wire used for thistuning voltage application. That is, since the signal which appears inthe one terminal of the coil 132 is divided by the two variablecapacitance diodes 134 and 136, the signal component tuned by theparallel resonance circuit consisting of these elements appears also inthe two cathode sides of the variable capacitance diodes 134 and 136.Hence, the output signal of the tuning circuit 130 is inputted into thepad 112 of the semiconductor device 100 via the connection wire forapplication of the tuning voltage. Thus, the signal inputted into thepad 112 is further sent to the processing circuit 114 via the capacitor120, and predetermined processing is performed.

In this manner, since it is possible to commonly use a pad for tuningvoltage application and a pad for input/output of a signal between thetuning circuit 130 and processing circuit 114 by outputting andinputting an output signal of this tuning circuit 130 by using theconnection wire of applying a tuning voltage to the variable capacitancediodes 134 and 136 which constitute the tuning circuit 130, it ispossible to reduce the number of pads of the semiconductor device 100which are used for connection with the tuning circuit 130.

In particular, in a general receiver, the number of pads of the entiresemiconductor device 100 can be sharply reduced by reducing the numberof pads according to respective sets since two or more sets of parallelresonance circuits by the coil 132 and variable capacitance diodes 134and 136 are provided in many cases.

In addition, since the processing circuit 114 included in thesemiconductor device 100, the digital-to-analog converter 122, pad 112,and capacitor 120 are formed on the semiconductor substrate 110, anotherpad for connecting these becomes unnecessary, and hence, it becomespossible to reduce the number of pads necessary in the entiresemiconductor device 100.

INDUSTRIAL APPLICABILITY

As mentioned above, according to the present invention, since it ispossible to commonly use a pad for tuning voltage application and a padfor input/output of a signal between the tuning circuit and processingcircuit by outputting and inputting an output signal of this tuningcircuit by using a connection wire of applying a tuning voltage to thevariable capacitance diodes which constitute the tuning circuit, it ispossible to reduce the number of pads of the semiconductor device whichare used for connection with the tuning circuit.

1. A receiver which has a tuning circuit and a semiconductor deviceincluding a processing circuit, into which an output signal of thistuning circuit is inputted, and a tuning voltage generating circuitwhich generates a tuning voltage changing a tuning frequency of thetuning circuit, the receiver characterized in that the tuning circuithas variable capacitance diodes whose electrostatic capacity is madevariable by the tuning voltage being applied; that the semiconductordevice has a common pad to which not only an output terminal of thetuning voltage generating circuit is connected, but also an inputterminal of the processing circuit is connected via a capacitor; andthat one terminal of the variable capacitance diodes and the pad areconnected.
 2. The receiver according to claim 1, characterized in thatthe processing circuit, the tuning voltage generating circuit, the pad,and the capacitor, included in the semiconductor device, are formed on asemiconductor substrate.
 3. The receiver according to claim 1,characterized in that the tuning circuit has a parallel resonancecircuit where a coil and the variable capacitance diodes areparallel-connected.
 4. The receiver according to claim 3, characterizedin that the tuning circuit is equipped with two or more sets of saidparallel resonance circuits.